SummaryPeptide YY3-36 (PYY3-36), a promising drug candidate for treatment of obesity, was administered subcutaneously in rats via tunable photocrosslinked poly(ester anhydride)s (PEAHs) which sustained PYY3-36 release and increased its subcutaneous bioavailability. By tuning hydrophobicity of the PEAH oligomers, in vivo release rate of PYY3-36 could be tailored as the release was controlled by the surface erosion of PEAHs. Micro-computed tomography (micro-CT) was used for visual and quantitative analysis of the surface erosion mechanisms of PEAHs. In conclusion, the present and earlier study indicate that photocrosslinked PEAHs enable tailored, surface erosion controlled drug delivery.